MEIOTIC DIPLOID PROGENY AND MEIOTIC NONDISJUNCTION IN SACCHAROMYCES CEREVISIAE

[摘要] Abnormalities in chromosome number that occurred during meiosis were evaluated with a specially-constructed diploid strain of Saccharomyces cerevisiae . The strain is heterozygous for six markers of the right arm of chromosome V and heterozygous for cyh2 (resistance to cycloheximide) on chromosome VII .—Selection of meiotic spores on a medium containing cycloheximide and required nutrilites—except those for the markers of the right arm of chromosome V —allows the growth of aberrant clones belonging only to two classes: a) diploid clones , caused by failure of the second meiotic division, with a frequency of 0.54 × 10-4 per viable spore; and b) diplo V , aneuploids derived from nondisjunctions in meiosis I or meiosis II, with a total spontaneous frequency of 0.95 × 10-4 per viable spore. About two-thirds of the aneuploids originated during meiosis I, the rest during meiosis II. An investigation of these events in control meioses and after treatment with MMS, Benomyl and Amphotericin B suggests that this assay system is suitable for screening environmental mutagens for their effects on meiotic segregation.

[学科分类] 医学（综合）